1. Field of the Invention
The invention concerns a modulator for the amplitude or phase modulation of an electromagnetic wave, especially in the range extending from visible to far infrared waves. The wave to be modulated may be a guided wave or a free wave.
2. Description of the Prior Art
There are known methods for making modulators working in the medium infrared range and using an injection of carriers. This type of modulator has a limited pass-band because of the long lifetime of the carriers. There are also known methods for making modulators with electro-optical effect. This is a very fast effect, but a pass-band corresponding to the quickness of this effect cannot be obtained because these modulators have electrodes designed to apply an electric field, and these electrodes have relatively high capacitance values.
In standard modulators, the pass-band depends on the dimensions of the modulator. This problem of pass-bands is aggravated when the wavelength increases because the dimensions of a modulator increase with the wavelength of the wave to be modulated. In particular, it is far more difficult to make a modulator for waves in the medium infrared range than to make one for waves in the visible or near infrared range.
The aim of the invention is to propose a modulator with a wider pass-band than that of standard modulators for waves in the medium or far infrared range.